This is huge collection of 1000+ free courses online for more than 25+ subjects of your interest. Some courses are offered with free credit/degree/certificate of accomplishment/completion. Every course has full lenght video tutorials/lectures, some of them have assignments, lecture notes and Quizzes as well. Courses are from Ivy League universities and best colleges like MIT, Yale, UC Berkeley, NPTEL, Harvard, Stanford, McGill etc... and some are from individuals like Khan Academy and Patric Dixon.